The 3rd Generation Partnership Project (3GPP) Evolved Packet System (EPS) is composed of an Evolved Universal mobile communication system Terrestrial Radio Access Network (E-UTRAN), a Mobility Management Entity (MME), a Serving Gateway (S-GW), a Packet Data Network Gateway (P-GW or PDN GW), a Home Subscriber Server (HSS), an Authentication, Authorization and Accounting (AAA) server of 3GPP, a Policy and Charging Rules Function (PCRF) entity and other supporting nodes.
FIG. 1 is a schematic diagram of a system architecture of EPS. As shown in FIG. 1, the mobility management entity is responsible for the relative operations of the control plane such as mobility management, processing for non-access stratum signaling and management of user mobility management context; the S-GW is an access gateway device connected with the E-UTRAN, is used to forward data between the E-UTRAN and the P-GW, and is responsible for buffering the paging wait data; the P-GW is a border gateway between the EPS and the packet data network (PDN), is responsible for functions of the access of PDN and forwarding data between the EPS and the PDN, etc.; both the S-GW and the P-GW are belong to the core network gateway; the PCRF connects with the operator internet protocol (IP) service network through receiving interface Rx to obtain service information, and moreover, it connects with the gateway devices in the network through interfaces Gx, Gxa and Gxc, and is responsible for initiating establishment of IP bearer, guaranteeing the quality of service (QoS) of the service data and performing charging control.
The EPS supports intercommunication with a non-3GPP system, wherein, the intercommunication with the non-3GPP system is realized through interfaces S2a, S2b and S2c, and the P-GW acts as an anchor point between the 3GPP system and the non-3GPP system. In the system architecture diagram of EPS, the non-3GPP system is divided into a trusted non-3GPP IP access and an un-trusted non-3GPP IP access. The trusted non-3GPP IP access can connect with the P-GW through the S2a interface; and the un-trusted non-3GPP IP access needs to connect with the P-GW through an evolved packet data gateway (ePDG), and the interface between the ePDG and the P-GW is S2b. S2c provides control related to the user plane and mobility support between the user equipment (UE) and the P-GW, the supporting mobility management protocol is a mobile IPv6 support for dual stack hosts and routers (DSMIPv6).
In the EPS system, a policy and charging enforcement function (PCEF for short) entity exists in the P-GW, and information is exchanged between the PCRF and the P-GW through a Gx interface (see FIG. 1). When the interface between the P-GW and the S-GW is based on PMIPv6, the S-GW has a bearer binding and event report function (BBERF) entity to perform the QoS control on the service data stream, and the information is exchanged between the S-GW and the PCRF through a Gxc interface (see FIG. 1). When accessing by the trusted non-3GPP access system, the BBERF also residents in the trusted non-3GPP access gateway. The information is exchanged between the trusted non-3GPP access gateway and the PCRF through the Gxa interface (see FIG. 1). When the UE is roaming, a interface S9 is the interface of a home PCRF and a visit PCRF, meanwhile an application function (AF) of providing services for the UE sends the service information used for constituting a policy and charging control (PCC) strategy to the PCRF through the interface Rx. In the 3GPP, the corresponding PDN network can be found by an access point name (APN). One connection from the UE to the PDN network is usually called as an IP connectivity access network (IP-CAN) session. During establishing the IP-CAN session, Diameter sessions are established respectively between the BBERF and the PCRF and between the PCEF and the PCRF, information, such as the policy charging information and the information used to constitute the policy, etc., used for controlling the IP-CAN session is transported by these Diameter sessions.
Home eNodeB (H(e)NB) is a small, low power base station deployed in indoor places such as home and office, the main action is to provide higher service rate for users and reduce cost required for using the high rate service, and meanwhile it compensates coverage shortage of the existing distributed cell wireless communication system. The advantages of the H(e)NB are economy, convenience, low power output and plug and play, and so on. In the H(e)NB system, the H(e)NB is a network element of radio side.
Local IP Access (LIPA) is a technology proposed in H(e)NB research, as shown in FIG. 2. With LIPA technology, the local access by the terminal to other IP devices in the home area network of user and the intranet or the Internet can be realized, while the data stream does not need to cross the core network deployed by the operator. The local IP access can be realized by multiple connection establishment ways: by establishing a connection to realize the core network access and local IP access function at the same time (as shown in FIG. 2a and FIG. 2b), in which there is no need to add the function of local gateway to the radio side network element or the H(e)NB gateway, wherein the local access gateway, as the network of the local place accessing to the external network (such as internet), provides functions such as: address assignment, charging, packet filtering, strategy controlling, data distribution function, radio access network application part (NAS or RANAP) message parsing, network address translation (NAT) and local IP access strategy routing and enforcing, and so on; and, by adding the local gateway to provide strong support for the local IP access technology, the local gateway can be combined-set with the radio side network element (as shown in FIG. 2c). In the case that there is a H(e)NB gateway, the local gateway can not only be combined-set with the H(e)NB, but also can be combined-set with the H(e)NB gateway (as shown in FIG. 2d). The local gateway can be a local serving gateway (L-SGW) and a local packet data network (PDN) gateway (L-PGW), or can be a single L-PGW, or can be a data distribution function entity. Additionally, the H(e)NB gateway can be combined-set with the H(e)NB. For the universal terrestrial radio access network (UTRAN) system, the core network gateway can be a serving general packet radio service (GPRS) support node (SGSN), or a gateway PFRS support node (GGSN). The local gateway can be a local GGSN (L-GGSN) and a local SGSN (L-SGSN), or can be a single L-GGSN. For describing conveniently, and no matter for which way, the related network elements for establishing the LIPA connection include the radio side network element, the H(e)NB gateway and the local gateway, wherein the radio side network element, the H(e)NB gateway and the local gateway are belong to the network elements at which the UE is located when establishing the LIPA connection, which are called as the network elements at which the UE is located.
Because the data stream does not need to pass through the user plane channel of the core network, thereby decreasing the data flow load of the core network, so that not only the operator can provide services for the users by the more effective way, but also the user experience can be improved at the same time.